MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov
Contact: JPL/Martha J. Heil (818) 354-0850
NASA Headquarters/Donald Savage (202) 358-1547
FOR IMMEDIATE RELEASE July 17, 2002
INTERPLANETARY SUPERHIGHWAY MAKES SPACE TRAVEL SIMPLER
A "freeway" through the solar system resembling a vast array of virtual
winding tunnels and conduits around the Sun and planets, discovered by an
engineer at NASA's Jet Propulsion Laboratory, Pasadena, Calif., can slash the
amount of fuel needed for future space missions.
Called the Interplanetary Superhighway, the system was calculated by
Martin Lo, who used his theory to design the flight path for NASA's Genesis
mission, which is currently using this "freeway in space" on its mission to collect
solar wind particles for return to Earth.
Most missions are designed to take advantage of the way gravity pulls on a
spacecraft when it swings by a body such as a planet or moon. Lo's theory mixes
in another factor, the Sun's pull on the planets or a planet's pull on its nearby
moons. Forces from many directions nearly cancel each other out, leaving paths
through the gravity fields in which spacecraft can travel.
Each planet and moon has five locations in space called Lagrange points,
where one body's gravity balances another's. Spacecraft can orbit there while
burning very little fuel. To find the Interplanetary Superhighway, Lo mapped all
the possible flight paths among the Lagrange points, varying the distance the
spacecraft would go and how fast or slow it would travel. Like threads twisted
together to form a rope, the possible flight paths formed tubes in space. Lo plans
to map out these tubes for the whole solar system.
Lo has turned the theory of the Interplanetary Superhighway into a tool for
mission design called "LTool," using models developed at Purdue University,
West Lafayette, Ind. The new LTool designed the flight path for the Genesis
mission, the first space mission to use the theory of the Interplanetary
Superhighway. Genesis launched in August 2001.
The flight path was designed for the spacecraft to leave Earth and travel to
orbit the Lagrange point. After five loops around this Lagrange point, the
spacecraft will fall out of orbit without any maneuvers and then loop around Earth
to a Lagrange point on the opposite side of the planet. Finally, it will return to
Earth's upper atmosphere to drop off its samples of solar wind in the Utah desert,
at the Air Force's Utah Testing and Training Range.
"Genesis wouldn't need to use any fuel at all in a perfect world," Lo said.
"But since we can't control the many variables that occur throughout the mission,
we have to make some corrections as Genesis completes its loops around a
Lagrange point of Earth. The savings on the fuel translates into a better and
cheaper mission."
"It has been exciting and challenging to develop this field. Our work on the
Genesis mission is definitely a high point," said Kathleen Howell, co-creator of
LTool, and a professor of aeronautics and astronautics at Purdue. "The theory has
been known for some time, but this is the first time it has been applied to a space
mission."
"For all missions going to a Lagrange point, LTool will speed up
computations," Lo said. "Designing the Genesis spacecraft's flight path with
traditional methods used to take eight weeks, but now we can design a new flight
path in less than a day -- we have redesigned a whole mission in a week."
Lo envisions a place to construct and service science platforms around one
of the Moon's Lagrange points. Since the Lagrange points are landmarks for the
Interplanetary Superhighway, spacecraft could easily be shunted to and from the
station for repair. A team at NASA's Johnson Space Center, Houston, working
with the NASA Exploration Team, proposes to someday use the Interplanetary
Superhighway for future human space missions.
"Lo's work has led to breakthroughs in simplifying mission concepts for
human and robotic exploration beyond low-Earth orbit," said Doug Cooke,
manager of the Advanced Development office at Johnson. "These simplifications
result in fewer space vehicles needed for a broad range of mission options."
Lo's and Howell's work on the Interplanetary Superhighway for space
mission design was nominated for an annual Discover Innovation Award by
Discover magazine editors and an outside panel of experts.
Spacecraft are not the only users of the Interplanetary Superhighway:
asteroids and comets are known to travel on it. Comet Shoemaker-Levy 9 collided
with Jupiter when it took an off-ramp toward the giant gas planet. Scientists think
the asteroid that killed the dinosaurs could have followed Genesis' flight path -- an
iridium deposit at the crash site shows the asteroid traveled fairly slowly. It's just
what we might expect from an asteroid on the Interplanetary Superhighway, Lo
said.
For more information on the Genesis mission, visit:
http://www.genesismission.org .
JPL is managed for NASA by the California Institute of Technology,
Pasadena.
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2002-147
05/17/02 MJH